Angry Birds, the game, may have gone to various places and a lot of platforms including the web, Android and iOS but it will still take some time for the game to go live on Windows Phone 7 platform. Now we do not know the exact reasons for this as both Rovio (developers of Angry Birds) and Microsoft are citing different reasons which have lead to the delay of the game.
The game was initially slated to launch on May 25 on the Windows Phone 7 (as announced by Microsoft at the Mixx Conference). However, Microsoft now states that the delay in the launch is just because of the fact that they are working on giving an even better experience to users when the game finally hits the Windows Phone 7 app store. We feel that the delay may be because of the fact that Microsoft is planning an updated version of Windows Phone, codenamed “Mango”, just around that time (Mid 2011).
Well, Rovio has a different version of the story (about the delay). They say that it's Microsoft's legal team which is causing the delay. According to one Peter Vesterbacka at Rovio Microsoft used the Angry Birds logo without the permission of Rovio and later removed it saying it was a mistake.
Whatever the reason may be, Windows Phone 7 user, you have to wait for over a month now before you can get the Angry Birds experience on your devices. Till then you can enjoy Angry Birds on any web browser!